Hey guys.
this is my first post after my intro. Great forum. Here's the issue I'm facing. 2002 Jaguar X-type 3.0L petrol

manual. It might go to the shop soon if there I cant find out what's going on myself.
Battery was weak but car started with a boost from my booster pack. I let the car warm up and drove. It was somewhat under powered but I was in residential and not driving too hard to notice it much. Got onto a bigger road and car went into limp mode. Got home, changed the battery out with a new one because the old one failed. Now it goes in and out of limp mode and even when it's not in limp mode it is vastly under powered. A tick or misfire like sound can be heard from the passenger side exhaust out the back. I've checked fuses and listened for vac leaks and haven't found any issue there just yet. Any advice would be gratefully appreciated.

 

Can you get a code reader on it?
Could be a collapsing catalyst.
You can sometimes hear them rattling around if you shake the down pipe.
Then again it could be something else!

 

You normally cannot hear vac (air) leaks - use OBD as the many threads explain.

 

My code reader wouldn't connect to it. Might need a better one. Would there be codes present if it's not currently in limp mode? The check engine light has not come on at all. Just the amber light and the no cruise avail on display when it goes into limp.

 

Checking for air leaks is independent of whether there are codes and should be done either way.

Codes stay stored until cleared by an OBD device or 40 (may be 80) warm ups without fault. Which usually means they're there.

In limp mode it's trying to allow some power without doing severe damage. I suppose the alternative mode would be refusing to run at all. All the car knows is something is horribly wrong and urgently must be fixed. It doesn't want to write off the engine.

It dare not do cruise control when it's not even sure what is wrong.